Mode of Action of an exo-β-(1→3)-D-Glucanase on the Laminaran from Eisenia bicyclis

抄録

In the initial stage of hydrolysis, exo-β-(1→3)-D-glucanase from Basidiomycetes sp. QM806 cleaved laminaran from Eisenia bicyclis with a pattern resembling an erdo-hydrolase. Five kinds of intermediate gluco-oligosaccharides were separated by a combination of gel filtration and HPLC. They were shown to be 3²-O-β-D-glucosyl-gentiobiose, 3²-O-β-D-gentiobiosyl-gentiobiose, 3³-O-β-D-glucosyl-gentiotriose, 3⁴-O-β-D-glucosyl-3²-O-gentiobiosyl-gentiobiose, and 3³-O-β-D-gentiobiosylgentiotriose by enzymic hydrolysis and methylation analysis as well as by ¹³C NMRspectroscopy. As a result, such kinds of β(1→3)-β-(1→6)-linked oligosaccharides could be accounted for in the initial cleavage, and they were hydrolyzed ultimately to glucose, gentiobiose, and gentiotriose. It suggests that a single (1→3)-linkage on a block of (1→6)-links show some resistance to attack by this enzyme.